Cracks in Concrete Paving Blocks

Cracks in Concrete Paving Blocks and Concrete products.

One of the most common questions received on our Email is about Cracks in Concrete Paving Blocks that are developing in newly poured Concrete Paving Blocks. The homeowner will question why it is cracking and did they receive a shoddy job.

Please Note :- Use batter Quality Concrete admixtures

When installed properly, Concrete Paving Blocks is one of the most durable and long lasting products you can use around Out door area Near by your home, Pathway, Driveway, petrol pumps, Parking area. But it is important that Concrete Paving Blocks Manufactures follow well-established guidelines with respect to concrete placement. Durable Concrete Paving Blocks, high strength Concrete Paving Blocks , and crack resistant Concrete Paving Blocks does not happen by accident.

Cracks in Concret Paving Block

Cracks in Concret Paving Block

Why Cracks in Concrete Paving Blocks.

Reason #1 – Excess water use in the Mix of Concrete Paving Blocks raw material. 

Concrete mix does not require much water to achieve maximum strength. But a wide majority of concrete used in residential work has too much water added to the concrete on the job site. This water is added to make the concrete easier to install. This excess water also greatly reduces the strength of the Concrete Paving Blocks.

Shrinkage is a main cause of cracking in Concrete Paving Blocks. As concrete hardens and dries it shrinks. This is due to the evaporation of excess mixing water. The wetter or soupier the concrete mix, the greater the shrinkage will be. Concrete slabs can shrink as much as 1/2 inch per 100 feet. This shrinkage causes forces in the concrete which literally pull the slab apart. Cracks are the end result of these forces.

The bottom line is a low water to cement ratio is the number one issue effecting concrete quality- and excess water reduces this ratio.

What you can do about it:-

Know the allowable water for the mix the contractor is pouring- or be very sure you have chosen a reputable contractor who will make sure the proper mix is poured. It is more expensive to do it right- it simply takes more manpower to pour stiffer mixes.

Cracks in Concrete Paving Blocks

Cracks in Concrete Paving Blocks and Concrete Products.

Reason #2 – Rapid Drying of the Concrete Paving Blocks and Concrete Products.

Also, rapid drying of the slab will significantly increase the possibility of cracking. The chemical reaction, which causes concrete to go from the liquid or plastic state to a solid state, requires water. This chemical reaction, or hydration, continues to occur for days and weeks after you pour the concrete.

You can make sure that the necessary water is available for this reaction by adequately curing the slab,  Concrete Paving Blocks.

What you can do about it:-

Read here about the methods to cure concrete and understand how your contractor will cure the concrete and Concrete Paving Blocks.

Reason #3- Improper strength concrete poured on the job.

Concrete Paving Blocks and Concrete Products is available in many different strengths. Verify what strength the concrete you are pouring should be poured at.

Talk to the ready mix supplier.

Consult with the Ready Mix Concrete Association in your area.

Reason #4 – Lack of control joints.

Control joints help concrete crack where you want it to. The joints should be of the depth of the slab and no more than 2-3 times (in feet) of the thickness of the concrete (in inches). So 4″concrete should have joints 8-12′ apart.

Other reasons:-

Never pour concrete on frozen ground.

The ground upon which the concrete will be placed must be compacted.

The sub grade must be prepared according to your soil conditions. Some flatwork can be poured right on native grade. In other areas 6″of base fill is required along with steel rebar installed in the slab.

Understand what you contractor is doing about each of the above listed items and you will get a good concrete job.